Absorption Process in MgCl2–NH3 Thermochemical Batteries With Constant Mass Flow Rate

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
Seyyed Ali Hedayat Mofidi ◽  
Kent S. Udell
Keyword(s):  
Mass Transfer ◽  
Mass Flow Rate ◽  
Reaction Zone ◽  
Mass Flow ◽  
Flow Rate ◽  
Absorption Rate ◽  
Constant Mass ◽  
Absorption Process ◽  
Cell Reactor ◽  
Series Of Experiments

In this paper, the performance of a thermochemical battery based on magnesium chloride and ammonia pair with a constant mass flow rate of ammonia gas is studied through a series of experiments using single and multicell configurations. It is shown that a lower mass flow rate lowers the temperature of the reactive complex and increases the duration of the absorption process. However, it was observed that the reaction eventually becomes mass transfer limited which slows the absorption rate to values below those specified by the mass flow controller (MFC). It was shown in the single-cell reactor that a reaction zone starts at the inlet and moves toward the end of the reactor. The mass transfer limited reaction zone movement reduces the absorption rate and temperature in the reaction zone. The overall performance of a multicell thermal battery is also studied to analyze behavior of such reactors as well. It was shown that the controlling the flow rate of ammonia can cause the cells to deviate in absorption rate.

Absorption Process in MgCl2-NH3 Thermochemical Batteries With Constant Mass Flow Rate

2018 ◽  
Author(s):  
Seyyed Ali Hedayat Mofidi ◽  
Kent S. Udell
Keyword(s):  
Mass Transfer ◽  
Mass Flow Rate ◽  
Reaction Zone ◽  
Mass Flow ◽  
Flow Rate ◽  
Absorption Rate ◽  
Constant Mass ◽  
Absorption Process ◽  
Thermal Batteries ◽  
And Performance

The working principle and performance of thermochemical batteries have been studied before [1–3]. In this paper, the performance of a thermochemical battery based on magnesium chloride and ammonia pair with a constant mass flow rate of ammonia gas is studied. It is shown that controlling the mass flow rate lowers the temperature of the reactive complex and increases the duration of the absorption process. However, it was observed that the reaction becomes mass transfer limited which slows the absorption rate and takes control of the reaction away from the mass flow controller. The progress of the reaction inside the reactor is studied in a single-cell reactor to understand the performance of these thermal batteries. It was shown that a reaction zone starts at the inlet and moves toward the end of the reactor. The mass transfer limited reaction zone movement reduces the absorption rate and temperature in the reaction zone.

Research on Two-Phase Flow Instability in Evaporator of Refrigeration System

2010 ◽  
Author(s):  
Nan Liang ◽  
Changqing Tian ◽  
Shuangquan Shao
Keyword(s):  
Pressure Drop ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Two Phase Flow ◽  
Density Wave ◽  
Phase Flow ◽  
Constant Mass ◽  
Refrigeration System ◽  
Two Phase

As one kind of fluid machinery related to the two-phase flow, the refrigeration system encounters more problems of instability. It is essential to ensure the stability of the refrigeration systems for the operation and efficiency. This paper presents the experimental investigation on the static and dynamic instability in an evaporator of refrigeration system. The static instability experiments showed that the oscillatory period and swing of the mixture-vapor transition point by observation with a camera through the transparent quartz glass tube at the outlet of the evaporator. The pressure drop versus mass flow rate curves of refrigerant two phase flow in the evaporator were obtained with a negative slope region in addition to two positive slope regions, thus making the flow rate a multi-valued function of the pressure drop. For dynamic instabilities in the evaporation process, three types of oscillations (density wave type, pressure drop type and thermal type) were observed at different mass flow rates and heat fluxes, which can be represented in the pressure drop versus mass flow rate curves. For the dynamic instabilities, density wave oscillations happen when the heat flux is high with the constant mass flow rate. Thermal oscillations happen when the heat flux is correspondingly low with constant mass flow rate. Though the refrigeration system do not have special tank, the accumulator and receiver provide enough compressible volume to induce the pressure drop oscillations. The representation and characteristic of each oscillation type were also analyzed in the paper.

scholarly journals Thermal and Cost Analysis of a Multi-Pass Solar Air Heater with Reversed Absorber and Reflector

2020 ◽  
pp. 141-146
Keyword(s):  
Cost Analysis ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Cost Effective ◽  
Solar Air Heater ◽  
Constant Mass ◽  
Air Heater ◽  
Effectiveness Model ◽  
Solar Intensity

Solar air heater is a major component of solar dryer. A model of multi pass solar air heater (MPSAH) with reversed absorber and reflector was developed. Exhaustive Study over the performance of MPSAH with and without reversed absorber and cost analysis was done. The performance curves show the effect of solar intensity on MPSAH with and without reversed absorber at constant mass flow. It was observed that the thermal efficiency of MPSAH is depending on solar intensity and losses when mass flow rate remain constant. At constant mass flow rate 26.90 gm/sec, the collector efficiency increased by 9% at average solar intensity 457w/m². Theoretical and experimental analysis showed close agreement. In addition the cost-effectiveness model has been used to examine the performance MPSAH with and without reverse absorbers. The air heaters annual cost (AC) estimation and annual power acquirement (AG) was analyze. The result is evidence for that multi-pass solar air heater with reverse absorbers and reflector is more cost-effective than multi-pass solar collectors without reverse absorber.

scholarly journals Experimental Study of a Bubble Mode Absorption with an Inner Vapor Distributor in a Plate Heat Exchanger-Type Absorber with NH3-LiNO3

Energies ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 2137 ◽  
Author(s):  
Jorge Chan ◽  
Roberto Best ◽  
Jesús Cerezo ◽  
Mario Barrera ◽  
Francisco Lezama
Keyword(s):  
Mass Transfer ◽  
Experimental Study ◽  
Heat Exchanger ◽  
Transfer Coefficient ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Plate Heat Exchanger ◽  
Ammonia Vapor ◽  
Plate Heat

Absorption systems are a sustainable solution as solar driven air conditioning devices in places with warm climatic conditions, however, the reliability of these systems must be improved. The absorbing component has a significant effect on the cycle performance, as this process is complex and needs efficient heat exchangers. This paper presents an experimental study of a bubble mode absorption in a plate heat exchanger (PHE)-type absorber with NH3-LiNO3 using a vapor distributor in order to increase the mass transfer at solar cooling operating conditions. The vapor distributor had a diameter of 0.005 m with five perforations distributed uniformly along the tube. Experiments were carried out using a corrugated plate heat exchanger model NB51, with three channels, where the ammonia vapor was injected in a bubble mode into the solution in the central channel. The range of solution concentrations and mass flow rates of the dilute solution were from 35 to 50% weight and 11.69 to 35.46 × 10−3 kg·s−1, respectively. The mass flow rate of ammonia vapor was from 0.79 to 4.92 × 10−3 kg·s−1 and the mass flow rate of cooling water was fixed at 0.31 kg·s−1. The results achieved for the absorbed flux was 0.015 to 0.024 kg m−2·s−1 and the values obtained for the mass transfer coefficient were in the order of 0.036 to 0.059 m·s−1. The solution heat transfer coefficient values were obtained from 0.9 to 1.8 kW·m−2·K−1 under transition conditions and from 0.96 to 3.16 kW·m−2·K−1 at turbulent conditions. Nusselt number correlations were obtained based on experimental data during the absorption process with the NH3-LiNO3 working pair.

scholarly journals Numerical Study of a Thermosyphon Cooling System: film condensation

2018 ◽  
Vol 42 ◽  
pp. 01005
Author(s):  
Filian Arbiyani
Keyword(s):  
Nusselt Number ◽  
Standard Deviation ◽  
Water Temperature ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Reynold Number ◽  
Film Condensation ◽  
Constant Mass ◽  
Cooling Systems

Studies of condensation in several cooling systems have been conducted. However, the mode of condensation in two-phase cooling systems to achieve a high rate of condensation in compact devices has not been explored. Condensation phenomena, indeed, is a key parameter in designing a thermosyphon water cooled condenser system. The analysis of this condensation phenomena has been done numerically by implementing the governing equations and boundary conditions in commercial MATLAB software. Steady-state laminar film condensation on the radial system is assumed as a condensation phenomenon between vapor and the outer surface of coolant coil. There is a good agreement between experimental and simulation results. Furthermore, for 0.3 LPM 10 °C, it is found the standard deviation of 0.3 %. This small standard deviation indicates the good accuracy of the simulation. At a constant mass flow rate of water, the higher inlet water temperature will result in a higher Nusselt number of water. Furthermore, at the same Nusselt number of water, the lower inlet water temperature obtained a higher film condensation rate. Nusselt number of film condensation increases as the Nusselt number of water decreases at the various constant of mass flow rate of water. Additionally, the lower inlet water temperature will result in a lower Nusselt number of water. The value of Reynold number film condensation increases as Reynold numbers and Nusselt number of water increase. At various constant mass flow rates of the water, at the same Nusselt number of water, the Reynold number of film condensation increases with lower inlet water temperature. The lower inlet water temperature increases the value of Reynold number of film condensation leading to more wavy and turbulent flow. The present study provides guidelines for thermal management engineers to design and fabricate compact cooling systems.

scholarly journals Ignition and Flame Stabilization of a Strut-Jet RBCC Combustor with Small Rocket Exhaust

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Jichao Hu ◽  
Juntao Chang ◽  
Wen Bao
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Flame Stabilization ◽  
Combined Cycle ◽  
Pure Oxygen ◽  
Pilot Method ◽  
Total Temperature ◽  
Series Of Experiments ◽  
Rocket Exhaust

A Rocket Based Combined Cycle combustor model is tested at a ground direct connected rig to investigate the flame holding characteristics with a small rocket exhaust using liquid kerosene. The total temperature and the Mach number of the vitiated air flow, at exit of the nozzle are 1505 K and 2.6, respectively. The rocket base is embedded in a fuel injecting strut and mounted in the center of the combustor. The wall of the combustor is flush, without any reward step or cavity, so the strut-jet is used to make sure of the flame stabilization of the second combustion. Mass flow rate of the kerosene and oxygen injected into the rocket is set to be a small value, below 10% of the total fuel when the equivalence ratio of the second combustion is 1. The experiment has generated two different kinds of rocket exhaust: fuel rich and pure oxygen. Experiment result has shown that, with a relative small total mass flow rate of the rocket, the fuel rich rocket plume is not suitable for ignition and flame stabilization, while an oxygen plume condition is suitable. Then the paper conducts a series of experiments to investigate the combustion characteristics under this oxygen pilot method and found that the flame stabilization characteristics are different at different combustion modes.

scholarly journals Air Bag Momentum Force Including Aspiration

1995 ◽  
Vol 2 (2) ◽  
pp. 99-109
Author(s):  
Guy Nusholtz ◽  
Deguan Wang ◽  
E. Benjamin Wylie
Keyword(s):  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Sampling Procedure ◽  
Gas Jet ◽  
Cfd Model ◽  
System A ◽  
Jet Behavior ◽  
Series Of Experiments ◽  
Air Bag

A gas-jet momentum force drives the air bag into position during a crash. The magnitude of this force can change as a result of aspiration. To determine the potential magnitude of the effect on the momentum force and mass flow rate in an aspirated system, a series of experiments and simulations of those experiments was conducted. The simulation consists of a two-dimensional unsteady isentropic CFD model with special “infinite boundaries”. One of the difficulties in simulating the gas-jet behavior is determining the mass flow rate. To improve the reliability of the mass flow rate input to the simulation, a sampling procedure involving multiple tests was used, and an average of the tests was adopted.

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